There is an increasing demand for tamper-indicating systems which ensure that a container is not re-filled with non-original contents. Whilst it is relatively easy to produce some form of tamper-evidence, it is much more difficult to provide a closure with tamper-evidence which cannot be either overcome without causing the tamper-evidence system to activate, or activated and then returned to a virtually visually identical state so as to appear non-activated.
A particularly useful method of providing tamper-evidence is to use a system in which a closure is initially located in a first position, but once removed can only be returned to a second position which is visually distinct from the first. Such tamper-evident systems are only effective if they cannot be reversed. For example, in systems which use an obstructing member to hold two parts apart it is possible to cut the obstruction to allow a gap to be closed.
International Patent Publication Nos. WO 2005/049443 and WO 2006/117505 describe closures which generate a gap upon first opening of the closure to indicate that the closure has been opened at least once. The closures generate unobstructed gaps following relative rotation of one part with respect to another. In other words, two parts of the closure are held apart without the requirement of an obstruction. The closures are provided with some internal mechanism for preventing the two parts from being rotated back to their original relative positions.
International Patent Publication No. WO 2014/170284 describes a closure comprising a shell having a distortable portion that is distorted upon first opening of the closure to indicate that the closure has been opened at least once.
It is an object of the present invention to provide further improvements relating to a closure for a container neck.